Find the free electron concentration in ionsphere if its refractive index is equal to `n = 0.90` for radiowaves of frequency `v = 100 MHz`.

Explanation

From the previous problem
`n^(2) = 1-(n_(0)e^(2))/(epsilon_(0) momega^(2))`
`=1 - (n_(0)e^(2))/(4pi^(2)epsilon_(0)mv^(2))`
Thus `n_(0) = (4pi^(2)v^(2)m epsilon_(0)//e^(2)) (1-n^(2)) = 2.36 xx 10^(7)cm^(-3)`